Pycnocraspedum rowleyensis, Schwarzhans & Psomadakis & Nielsen, 2025

Schwarzhans, Werner W., Psomadakis, Peter N. & Nielsen, Jørgen G., 2025, Revision of the bathydemersal fish genus Pycnocraspedum (Ophidiidae; Teleostei), with description of two new species, Zootaxa 5636 (3), pp. 443-472 : 464-465

Pycnocraspedum rowleyensis sp. nov.

Figures 3 , 5 , 10 , 12; Tables 1 , 2

Material examined ( holotype, 235 mm SL): WAM P28058.021 , 18°05'S, 118°10'E, West Australia, approximately 80 km southwest of Rowley Shoals, 400 m, P. Berry and N. Sinclair, 17 August 1983 .

Diagnosis. Precaudal vertebrae 12, total vertebrae 52; dorsal-fin rays 87; anal-fin rays 69; pectoral-fin rays 25; long gill rakers on first gill arch 4; pseudobranchial filaments 4–5; 2 dorsal-fin rays in front of first vertebra; HL 25.3% of SL; body depth at vent 18.9% of SL; predorsal length 23% of SL; transverse scale rows above origin of anal fin 70, and above lateral line 17; broad expansion on preopercular angle with two spines, concave section above spine 2 without fleshy flap on hind margin of preopercle; otolith (16.5 mm in length) OL:OH = 2.1, dorsal rim crenulated.

Description (only additions to diagnosis). Relatively robust fish with moderately long tapering tail and rounded snout. Size of unique holotype 235 mm SL.

Meristics: caudal-fin rays 10; D/A = 25; V/A = 17.

Morphometrics in % of SL: diameter of orbit 3.9; upper jaw length 14.3; interorbital width 7; pelvic-fin base to anal-fin base 28.7; preanal length 50.2; prepelvic length 24.8; pectoral-fin length 15; pelvic-fin length 13.7.

Otolith morphology (holotype). Size 16.5 mm in length; OL:OH = 2.1; OH:OT = 2.35. Moderately thin, oval, elongated, anteriorly and posteriorly moderately and equally projecting. Dorsal rim rounded, intensely crenulated. Ventral rim smooth at center, anteriorly and posteriorly finely crenulated, shallower than dorsal rim. Inner face moderately bent in horizontal and vertical directions, with long, narrow, undivided sulcus reaching close to anterior and posterior rims of otolith. Sulcus with shallow, undivided, uniform colliculum with slightly concave dorsal rim and slightly convex ventral rim and rounded anterior and posterior tips. OL:CL = 1.45. Dorsal field with indistinct depression and deeply ingressing radial furrows; ventral field with faint radial furrows anteriorly and posteriorly. Outer face slightly convex with few radial furrows, and centrally with tubercles.

Coloration. Live coloration unknown. Color of preserved specimens medium brown.

Discussion. Pycnocraspedum rowleyensis belongs to a group of species in the genus with two preopercular spines positioned at lower corner of the margin of the preopercle. The single specimen from off northwestern Australia resembles P. africanum in many aspects but differs from the latter in the lower number of transverse scale rows (70 vs. 85–90) and scale rows above the lateral line (17 vs. 22-23), the concave stretch of the rear margin of the preopercle above the preopercular spines (vs. presence of a fleshy flap) and the more compressed otolith shape (OL:OH = 2.1 vs. 2.5–2.7).

Distribution. Pycnocraspedum rowleyensis is only known from the holotype caught off the Rowley shoals off northwestern Australia.

Etymology. Named after the Rowley Shoals, Western Australia, from where the holotype was obtained.

Figures

FIGURE 3. Detail figures and drawings of preopercular spines and lower preopercular pores in Pycnocraspedum; preopercular spines are numbered from 1 through 4 from the lower angle of the preoperculum upwards; abbreviation lpp = lower preopercular pore. 3A–3B) Pycnocraspedum armatum, USNM 227412, 3A1-3A2 specimen 1 left side, 3A3 specimen 1 right side (mirror imaged), 3B specimen 2; 3C–3D) Pycnocraspedum phyllosoma, 3C USNM 421587, 3D USNM 421586; 3E) Pycnocraspedum fulvum (holotype), BSKU 27497; 3F–3G) Pycnocraspedum africanum sp. nov., 3F holotype, MNHN 2000-5691, 3G paratype, MNHN 2000-5692; 3H) Pycnocraspedum rowleyensis sp. nov., holotype, WAM I.28059.021; 3I–3K) Pycnocraspedum squamipinne, 3I lectotype, BMNH 1890.7.31.1, 3J ZMUC P771871, 3K ZMUC P771737.

FIGURE 5. Otoliths, inner faces (if not noted otherwise) shown from right side. 5A–5C) Pycnocraspedum africanum sp. nov., 5A holotype, MNHN 2000-5691 (5A2 dorsal view), 5B paratype MNHN 2000-5692, 5C tentatively assigned specimen, IRSNB (5C2 dorsal view, 5C3 anterior view); 5D–5E) Pycnocraspedum armatum, 5D USNM 227412 (5D2 ventral view), 5E USNM 227390 (5E2 ventral view); 5F) Pycnocraspedum fulvum (holotype), BSKU 27497 (5F2 ventral view, 5F3 anterior view); 5G) Pycnocraspedum rowleyensis sp. nov., holotype, WAM I.28059.021 (5G2 ventral view); 5H) Pycnocraspedum phyllosoma, USNM 421587 (5H2 ventral view, 5H3 anterior view); 5I–5K) Pycnocraspedum squamipinne, 5I lectotype, BMNH 1890.7.31.1 (5I2 ventral view), 5J ZMUC P771871, 5L ZMUC P771739 (5L2 ventral view), 5K ZMUC P771738 (5K2 ventral view); 5M) †Pycnocraspedum cetonaense (holotype) SMF P.5694 (5M2 dorsal view, 5M3 anterior view).

FIGURE 10. Pycnocraspedum rowleyensis sp. nov.; 10A) holotype, WAM P28058.021, 18°05'S, 118°10'E, 400 m; 10B) radiograph of holotype.